Islands in ice: isolated populations of Cryptopygus sverdrupi (Collembola) among nunataks in the Sor Rondane Mountains, Dronning Maud Land, Antarctica

摘要

Molecular variation among Antarctic Collembola has been well appreciated over the last decade. The majority of studies have focussed on the Transantarctic Mountains and Antarctic Peninsula, and more recently Dronning Maud Land, which now accounts for all known continental species. Within most species, mean mitochondrial DNA (mtDNA) sequence divergence has not been more than around 2%, but in 2010 far greater levels of infraspecific sequence divergence (9.2-10.9%) were discovered in three species: Friesea grisea (10.2%), Gressittacantha terranova (10.4%) and Cryptopygus antarcticus (9.2%). Here, we present the first phylogeographic study on Cryptopygus sverdrupi from Dronning Maud Land. We found that mtDNA COI and 16S haplotypes clustered into two lineages with a mean COI sequence divergence of around 7.1%. The mixing of haplotypes between nearby nunataks separated by up to 15 km revealed support for ongoing (but rare) dispersal, although a single site, the most geographically isolated (by 40-58 km) was also the most genetically divergent. These levels of sequence divergence indicate persistence of biota throughout the Miocene and Pliocene isolated in glacial refugia. Expanding sampling of C. sverdrupi from additional ice-free refugia throughout Dronning Maud Land will be important to further our understanding of the evolutionary processes that have influenced the Antarctic continent, its landscape and biota.